feat(treemap): Enhance label formatter to include tile size

[netil]

Issue

#4066

Details

Updated the treemap label formatter to accept an additional parameter for tile size, allowing for more dynamic label rendering based on the width and height of the tiles. Updated documentation to reflect the new argument.

	treemap: {
		label: {
			format: function(value, ratio, id, size) {
				// size: {width, height} - tile dimension
				return `${id}\n${value}`;
			}
		}
	},

[coveralls]

coverage: 94.145% (-0.002%) from 94.147%
when pulling bc102de on netil:treemapLabel#4067
into 4379e29 on naver:master.